Spine and Peripheral Nerve

Spine and Peripheral Nerve

Spine Disorders

The spinal column is responsible for transmission of body weight from the head to the pelvis and protection of the spinal cord. The spinal column consists of bony vertebral bodies connected together by cartilage-like structures (discs) and ligaments. The spine is a mobile structure and its mobility depends on integrity of these structures. Variety of diseases can affect the spine and results in functional failure producing variety of symptoms and signs. Read here on Spine and Spinal Disorders. 

Degenerative Disease of the Spine (Spondylosis)

The spine is subjected to wear and tear like all joints in the body, with resultant changes in the structure. Degeneration of the disc may cause it to bulge and compress spinal cord or nerves. This will produce pain in the neck, back, arm or leg, even numbness or weakness. These degenerative disorders are diagnosed through physical examination and confirmed by imaging studies. Degenerative disease usually occurs in the cervical (neck) and lumbar (lower back) region of the spinal column as these are areas that underdo repetitive stess injuries and hence wear and tear.

Disc Herniation

The neck is subject to tension and pressure when the neck moves. The disc between each vertebra responds by acting as a shock absorber. Bending the neck forward compresses the discs between the vertebrae and tends to bulge the discs backward toward the spinal canal and nerve roots.

Problems may occur when the center part of the disc, the nucleus pulposus, squeezes out of the disc and puts pressure on nerves in the neck. This condition, called disc herniation, can happen when a tear in the outer ring of the disc (the annulus) allows the nucleus to squeeze through. The annulus can tear or rupture anywhere around the disc. If it tears next to the spinal canal, the nucleus can squeeze out and put pressure on the spinal cord or spinal nerves. Pressure against the nerve root from a herniated disc can cause numbness and weakness along the nerve. When the nerve root is inflamed, the added pressure from the disc may also cause vague, deep pain in the neck, shoulder, and upper arm. It can also cause sharp, shooting pain to radiate along the pathway of the nerve.

This condition may occur when too much force is exerted on an otherwise healthy intervertebral disc. Heavy forces on the neck may simply be too much for even a healthy disc to absorb. Herniated discs are more common in middle-aged adults. This is because the natural process of aging causes the discs to become weakened from degeneration. Less force is needed to cause the degenerated disc to herniate. Not everyone with a herniated disc has degenerative problems. Likewise, not everyone with degeneration will suffer a herniated disc.

Cervical Radiculopathy

Nerve roots that go from the spinal cord in the cervical spine travel into the arm. Along the way, these nerves supply sensation (feeling) to areas of the skin from the shoulder to the fingers. They also carry electrical signals to muscles that move the arm, hand, or fingers. Problems occur when one of these nerves becomes inflamed and is pinched by a herniated disc or bone spur. This may show up as weakness, numbness, and pain where the nerve travels. The pain may feel deep, dull, and achy. Or you may have sharp, shooting pain along the path of the nerve. Muscles controlled by the affected nerve root may also weaken. In the neck, this condition is called cervical radiculopathy. The same problem can also occur in the lower back and the problem is termed lumbar radiculopathy.

Finding the cause of the problem begins with a complete history and physical exam. After the history and physical exam, we will have a better idea about the cause of your pain or other symptoms. To make sure of the exact cause of your neck pain, several diagnostic tests can be used. Standard X-rays, are usually a first step in looking into any neck or back problem. These include an oblique (angled) view, along with X-rays taken as you bend forward (flexion) and backward (extension). Your doctor will also determine whether other tests, such as an MRI, are needed.

Treatment

Treatment in most cases consists of conservative methods such as rest, medications and physiotherapy. Intervention is indicated for severe symptoms or failure to respond to therapy. One option is nerve block techniques (injection of steroids or radiofrequency lesions) will help reduce or eliminate the pain. The final option is surgical treatment.

Surgical treatment involves decompressing the area of spine where degenerative changes have resulted in compression of the spinal cord or nerves and have resulted in the symptoms. It may also involve stabalisation of the bony components of the spinal cloumn with titanium plates and screws if the degree of wear has resulted in unstable bony architecture.

The two common types of surgery performed are via an anterior approach from the front or via a posterior approach from the behind.

In the anterior approach, the level of disc degeneration is identified and the disc or discs is removed during surgery under a microscope and the spinal cord is decompressed. The void space will be replaced with synthetic bone or with our own bone harvested from our hip. In certain circumstances when there are multiple disc herniations, the vertebral body together with the discs have to be removed and reconstructed with plates and screws. The anterior approach is usually performed more commonly for cervical disc degeneration.

In the posterior approach, the bony components are removed from behind the spinal cord inorder to achieve the decompression. The procedure where the bony components are completely removed is called a laminectomy. In certain cases, the bony components are not completely removed but are lifted up to allow more “room” for the compressed spinal cord. This procedure is called a laminoplasty.

Tumours of the Spine

This may include tumours of the spinal column or the spinal cord. Tumours may be primary (originating from the spine) or more commonly spread from other sites (such as liver, lung and breast). They produce a variety of symptoms, like back/leg pain, neurological symptoms (weakness, numbness, unsteady gait).

Treatment is dependent on the patient’s condition, extent of tumour and severity of symptoms. Surgical decompression to relieve spinal cord or nerve pressure may be needed to obtain relief from symptoms. Additional procedure may be needed to stabilise the spine. Further treatment with radiotherapy and chemotherapy may be necessary.

Spinal Trauma

Injuries to spine are common in road traffic accidents and falls from height. Spine fractures can cause pain or neurological deficits. Surgery is needed in cases where the spine is rendered unstable or there is a blood clot or prolapsed disc causing acute cord compression.

Carpal Tunnel Syndrome

Carpal Tunnel Syndrome (CTS) refers to the compression of the median nerve at the wrist in a structure called the carpal tunnel. The median nerve carries sensation from the palm surface of the thumb together with the index and middle finger. It also controls the muscles that move the thumb. The carpal tunnel is formed by wrist bones and a ligament called the flexor retinaculum that runs across the wrist. This "tunnel" is a narrow passageway for the median nerve as well as the many tendons that control finger movements. Swelling or thickening of any of the structures in or around the carpal tunnel may compress the median nerve, leading to pain, numbness and weakness of the hand and thumb.

Symptoms

The symptoms are often gradual in onset and often more severe in the dominant hand, presumably because it is used more often. Intermittent numbness or tingling is felt on the thumb, index, middle and ring fingers. This commonly occurs at night during sleep and improves by "shaking it off". Occasionally, the whole hand may feel as if it has "fallen asleep" or is "swollen". Symptoms can occur when holding objects, driving or reading. Patients also complain of intermittent weakness of the grip. In some individuals, the compression of the median nerve may worsen with time, resulting in permanent weakness and wasting of the thumb muscles.

Diagnosis

CTS can be confirmed by nerve conduction tests. It involves giving very small electric shocks to the median nerve and recording its electrical signals across the wrist. The test usually takes about half an hour. It is a safe procedure that does not require any sedation or anaesthesia.

Treatment

Most patients with mild to moderate CTS can be treated without surgery. Wearing a splint that keeps the wrist in a neutral position during sleep is recommended. Losing weight and repetitive movements of the hand and wrist (e.g. prolonged typing, knitting, SMS-ing on the handphone) should be avoided. Steroid injection into the carpal tunnel provides immediate but temporary relief in some people.

If the symptoms are severe or if there is significant nerve damage, surgical decompression should be considered. This involves cutting the flexor retinaculum and increasing the space in the carpal tunnel. This is a simple, effective, outpatient procedure that is performed under local anaesthesia. Complications of surgery are uncommon and include wound infection, nerve damage, stiffness and a painful scar. Most patients report improvement of symptoms after surgery.